You can see the knotted ropes that are installed in difficult, steep or slippery passages.­

Photo taken in the Clearwater cave system in Gunung Mulu National Park (Borneo)

The Clearwater System is believed to be the largest interconnected cave system in the world by volume and the 9th longest cave in the world at 189 Km (as of 2011).­ For more photos, information and cave map, view my Clearwater cave photo series.